题解 | #反转链表#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

/**
 * 
 * @param pHead ListNode类 
 * @return ListNode类
 */
struct ListNode* ReverseList(struct ListNode* pHead ) {
    // write code here
    if(pHead == NULL || pHead->next == NULL)
        return pHead;
    struct ListNode* tmp = pHead;
    struct ListNode* tmp1 = pHead->next;
    struct ListNode* tmppre = pHead;
    if(pHead->next->next ==NULL)
    {
        tmp = pHead->next;
        pHead->next->next = pHead;
        pHead->next = NULL;
        return tmp;
    }
    tmppre->next = NULL;
    while(tmp1)
    {
        tmp = tmp1;
        tmp1 = tmp1->next;
        tmp->next = tmppre;
        tmppre = tmp;
    }
    return tmp;
}